Why are my 15 mth old twins attached to my hip? HELP!!!?

We have a playroom in the basement. When I am with them they are constantly attached to me...want on my lap etc., and If I try to read or anything they scream until I hold them. As soon as I leave the room and they cannot see me, they stop crying immediately and go about playing on their own. When I come back they start the crying and needyness right away. What is going on? My husband says this doesn't happen when he is home...is he lying? all suggestions would be appreciated.